netdev - [PATCH net 1/2] netfilter: conntrack: skip identical origin tuple in same zone only

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Message-Id: <20210209213511.23298-2-pablo@netfilter.org>
Date:   Tue,  9 Feb 2021 22:35:10 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org
Subject: [PATCH net 1/2] netfilter: conntrack: skip identical origin tuple in same zone only

From: Florian Westphal <fw@...len.de>

The origin skip check needs to re-test the zone. Else, we might skip
a colliding tuple in the reply direction.

This only occurs when using 'directional zones' where origin tuples
reside in different zones but the reply tuples share the same zone.

This causes the new conntrack entry to be dropped at confirmation time
because NAT clash resolution was elided.

Fixes: 4e35c1cb9460240 ("netfilter: nf_nat: skip nat clash resolution for same-origin entries")
Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nf_conntrack_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 234b7cab37c3..ff0168736f6e 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1229,7 +1229,8 @@ nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple,
 			 * Let nf_ct_resolve_clash() deal with this later.
 			 */
 			if (nf_ct_tuple_equal(&ignored_conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
-					      &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple))
+					      &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple) &&
+					      nf_ct_zone_equal(ct, zone, IP_CT_DIR_ORIGINAL))
 				continue;
 
 			NF_CT_STAT_INC_ATOMIC(net, found);
-- 
2.20.1